The present invention relates to a process for treating a lithographic substrate, and more particularly, to a process for treating a lithographic substrate for a semiconductor device such as IC or LSI, a liquid-crystal panel device, or the like wherein a resist film is removed and then rinsed.
Further, it relates to the treatment of a substrate using such a rinse solution for lithography.
Conventionally, the process for manufacturing a semiconductor device such as an IC or LSI, or a liquid-crystal panel device includes the following steps of:
forming a conductive metallic film of aluminum, copper, aluminum alloy or the like, an insulating film of SiO.sub.2 or the like, etc. on a substrate;
uniformly applying a photoresist onto such films;
exposing the photoresist, or scanning the photoresist with electron rays, and then developing the resultant to form a resist pattern;
selectively etching the above-described conductive metallic film, insulating film, etc. using the obtained pattern as a mask, thus forming a fine circuit or the like; and then, removing the waste resist film with a remover solution.
In case where no ashing process is applied as described above, the waste resist film can be removed with a remover solution. Alternatively, in case where a dry etching and subsequently an ashing process are carried out, a degenerated resist film (by-product of dry etching adhered to the resist) is removed with a remover solution.
Examples of solutions for removing such a resist film include:
organic sulfonic-acid-based remover solutions in each of which the principal ingredient is an alkylbenzenesulfonic acid;
organic amine-based remover solutions wherein the principal ingredient is an organic amine such as monoethanolamine; and
hydrofluoric-acid-based remover solutions wherein the principal ingredient is hydrofluoric acid.
Organic sulfonic-acid-based remover solutions are difficult to handle and cause environmental problems since they are generally used in combination with another highly toxic organic solvent such as a phenolic compound, chlorobenzene, or the like. In addition, they readily corrode conductive metallic films and the like on the substrate.
Meanwhile, organic amine-based remover solutions are less toxic than organic sulfonic-acid-based remover solutions, and do not require a complicated procedure for waste disposal. And they exhibit excellent anticorrosion effects. Such remover solutions are, however, not sufficient at removing resist film which was treated by a process such as dry etching, ashing, or ion-implantation, and has degenerated to the extent that it exhibits inorganic properties. Moreover, since the removal treatment temperature when using such a remover solution is as high as 60 to 130.degree. C., combustible organic compounds in the remover solution may become volatile and because the danger of ignition, a great investment is necessary for facilities to prevent various disasters.
As for hydrofluoric-acid-based remover solutions whose principal ingredient is hydrofluoric acid, although they are superior at removing film degenerated to the extent that it exhibits inorganic properties, handling them is difficult since they are hazardous for humans and therefore difficult to handle. Further, since the compositions containing such a remover solution become acidic, peripheral apparatuses such as a chemical-solution-feeding apparatus communicated with a bath for removal treatment and a container for storage of the remover solution are readily corroded by the remover solution. In addition, complicated exhaust-gas treatment and waste-solution disposal are required.
As a remover solution for solving the above-described problems, the present inventors previously offered a remover solution in which the principal ingredient is a salt of a hydrofluoric acid and a metallic-ion-free base (hereinafter referred to as hydrofluorate remover solution) as described in a copending U.S. patent application Ser. No. 08/747,898. By using the hydrofluorate remover solution, the removal treatment can be performed at a low temperature and in a short period of time, thin metallic films on the substrate and peripheral apparatuses can be prevented from being corroded, and the exhaust-gas treatment and waste-solution disposal can be simplified. The hydrofluorate remover solution, however, corrodes thin metallic films such as those of Ti, Al, Al--Si, and Al--Si--Cu when the time for washing treatment with pure water after the removal treatment exceeds approximately 10 minutes. Further, if the washing treatment is performed using an organic solvent such as methanol, ethanol, isopropyl alcohol, or acetone, which have been conventionally used as a rinsing solution, instead of pure water, salts of hydrofluoric acid may be deposited on the substrate. Moreover, if the washing treatment is performed using ethylene glycol instead of pure water, the fine portions cannot be sufficiently washed because of its high viscosity, and it is difficult to completely wash off the remover solution.